A musical with an unlikeable leading man is off to a bad start before anyone has written a single line of dialogue of lyric. Unless that leading man is incredibly charismatic, I don't think it can work. I have seen 4 productions, including the Lena Horne one, and the leading man failed every time, in fact pretty miserably.
I agree with Pal Joey (who I always assumed absolutely loved the show) that the script has always been a problem; but even if someone manages to fix it, the leading man has to be right. (And the script has to deal with an unlikeable leading man role). I can't think of another musical HIT whose leading role was unlikeable. Will definitely have to be a small production, cause a big investment will lose more money than On The Town, which was joyous from beginning to end.
I also thought Dollypop's suggestion re Patti Lupone and Tony Yasbeck was right on; I disagree re Simard, who annoys me almost as much as Jackie Hoffman.